In this book, the problems of interaction of the electromagnetic field and substance are considered. This interaction is investigated on the basis of classical and quantum approaches. Standard methods, such as the classical electronic theory of interaction of the electromagnetic field with atoms; application of Maxwell equations to various problems; and research of effective sections of interaction are discussed. Questions regarding research of optical active substances, including the physical sense of the parameter of chirality and the relativistic theory of optical activity are analysed. Non-linear aspects of formation of electromagnetic impulse in dielectrics are submitted, including self-induced transparency. Decisions of some kinetic equations, including some for radiating gas are given. On the basis of quantum electrodynamics, the quantum-relativistic approach to an explanation of Malus law is developed, and some new features of deduction of the Klein-Nishina formula are investigated. The book can be useful to students and scientists working in areas connected with the interaction of electromagnetic radiation and substance.